// Mainly from Stockfish

#include <cassert>
#include <iostream>
#include "Move.h"
#include "Thread.h"

ThreadsManager Threads; // Global object



namespace { extern "C" {

	// start_routine() is the C function which is called when a new thread
	// is launched. It is a wrapper to member function pointed by start_fn.

	long start_routine(Thread* th) { (th->*(th->start_fn))(); return 0; }

} }


// Thread c'tor starts a newly-created thread of execution that will call
// the idle loop function pointed by start_fn going immediately to sleep.

Thread::Thread(Fn fn) {

	/*
	is_searching = do_exit = false;
	maxPly = splitPointsCnt = 0;
	curSplitPoint = NULL;
	*/
	start_fn = fn;
	idx = Threads.size();

	//do_sleep = (fn != &Thread::main_loop); // Avoid a race with start_searching()
	do_sleep = (fn != &Thread::BrainMainThreadLoop); // Avoid a race with start_searching()

	lock_init(sleepLock);
	cond_init(sleepCond);

	//for (int j = 0; j < MAX_SPLITPOINTS_PER_THREAD; j++)
	//    lock_init(splitPoints[j].lock);

	if (!thread_create(handle, start_routine, this))
	{
		std::cerr << "Failed to create thread number " << idx << std::endl;
		::exit(EXIT_FAILURE);
	}
	//cout << "Thread " << idx << " instance OK and ready to work !" << endl;
}


// Thread d'tor waits for thread termination before to return.
Thread::~Thread() {

	assert(do_sleep);

	do_exit = true; // Search must be already finished
	wake_up();

	thread_join(handle); // Wait for thread termination

	lock_destroy(sleepLock);
	cond_destroy(sleepCond);

	/*
	for (int j = 0; j < MAX_SPLITPOINTS_PER_THREAD; j++)
	lock_destroy(splitPoints[j].lock);
	*/ 
}


// Thread::timer_loop() is where the timer thread waits maxPly milliseconds and
// then calls check_time(). If maxPly is 0 thread sleeps until is woken up.
extern void check_time();

void Thread::ClockThreadLoop(){
//void Thread::timer_loop() {
	/*
	while (!do_exit)
	{
	while(ChessEngine.brainStatus != THINKING && !do_exit) Sleep(100);
	if(do_exit) return;
	cout << ">>> Timer started <<<" << endl;

	Sleep(ChessEngine.thinkDelay);
	ChessEngine.brainStatus = PAUSED;

	lock_grab(sleepLock);
	Sleep(ChessEngine.thinkDelay);
	//timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
	ChessEngine.brainStatus = PAUSED;
	lock_release(sleepLock);

	//check_time();
	cout << ">>> Timer stopped <<<" << endl;
	}*/

	// TODO: QUITTING could be cleaner
	while (ChessEngine.brainStatus != QUITTING)
	{
		while ((ChessEngine.brainStatus != THINKING) 
			&& (ChessEngine.brainStatus != QUITTING))
		{
			//cout << "Waiting..." << endl;
			Sleep(100);
			//Thread.Sleep(100);
		}

		if(ChessEngine.brainMode == MOVETIME_MODE
			|| ChessEngine.brainMode == ADJUSTTIME_MODE)
		{
			//cout << "Starting MOVETIME_MODE" << endl;
			// the search can be manually stopped via the command line
			// so a Sleep(thinkDelay) is not accurate enough
			// we need to check regularly if the brain was not stop by another way
			while (ChessEngine.watch.GetElapsedTime() < ChessEngine.thinkDelay
				&& ChessEngine.brainStatus == THINKING)
			{
				Sleep(100);
				//Thread.Sleep(100);
			} 
			//cout << "Stopping MOVETIME_MODE" << endl;
			ChessEngine.brainStatus = PAUSED;
		}
		else if(ChessEngine.brainMode == INFINITE_MODE)
		{
			//cout << "Starting INFINITE_MODE" << endl;
			// the search can be manually stopped via the command line
			// so a Sleep(thinkDelay) is not accurate enough
			// we need to check regularly if the brain was not stop by another way
			while (ChessEngine.brainStatus == THINKING)
			{
				Sleep(100);
				//Thread.Sleep(100);
			} 
			//cout << "Stopping INFINITE_MODE" << endl;
			ChessEngine.brainStatus = PAUSED;
		}
	}
}

//
//// Thread::main_loop() is where the main thread is parked waiting to be started
//// when there is a new search. Main thread will launch all the slave threads.
//
//void Thread::main_loop() {
//
//	ChessEngine.BrainMainThreadLoop();
//
//	/*
//	cout << "Main thread loop launched" << endl;
//	while (true)
//	{
//
//	lock_grab(sleepLock);
//
//	cout << "Stop thinking" << endl;
//	do_sleep = true; // Always return to sleep after a search
//	is_searching = false;
//
//	while (do_sleep && !do_exit)
//	{
//	cond_signal(Threads.sleepCond); // Wake up UI thread if needed
//	cond_wait(sleepCond, sleepLock);
//	}
//
//	lock_release(sleepLock);
//
//	if (do_exit)
//	return;
//
//	is_searching = true;
//
//	cout << "Start thinking" << endl;
//
//	//===================================== CUSTOM TEMP CODE
//	vector<Move> legalMoves;
//	GetLegalMoves(ChessEngine.currPos,legalMoves);
//	ChessEngine.InitPossibleNodes(legalMoves);
//	ChessEngine.brainStatus = THINKING;
//	//===================================== CUSTOM TEMP CODE
//	//Search::think();
//
//	}*/
//}


// Main thread - launch the different search modes
void Thread::BrainMainThreadLoop()
{
	// TODO: make QUITTING cleaner
	while (ChessEngine.brainStatus != QUITTING)
	{
		// wait loop
		while ((ChessEngine.brainStatus != THINKING) 
			&& (ChessEngine.brainStatus != QUITTING))
		{
			Sleep(100);
			//cout << "waiting..." << endl;
			//Thread.Sleep(100);
		}

		// Thread main task

		// global value
		ChessEngine.bestMove = MOVE_NULL;
		ChessEngine.bestScore = 0;
		int depth;
		ReturnCode searchResult = OK;
		switch (ChessEngine.brainMode)
		{
		case ADJUSTTIME_MODE:
		case MOVETIME_MODE:

			depth = 1;
			while (searchResult == OK
				&& ChessEngine.brainStatus == THINKING)
			{
				searchResult = ChessEngine.Search(ChessEngine.currentPosition, depth);
				depth++;
			}

			break;
		case MATE_MODE:
		case DEPTH_MODE:
			depth = 1;
			while (ChessEngine.brainStatus == THINKING && depth <= ChessEngine.depthLevel)
			{
				ChessEngine.Search(ChessEngine.currentPosition, depth);
				depth++;
			}
			break;
		case NODES_MODE:
			depth = 1;
			while (ChessEngine.brainStatus == THINKING && ChessEngine.nbProcessedNodes < ChessEngine.nodeMaxNumber)
			{
				ChessEngine.Search(ChessEngine.currentPosition, depth);
				depth++;
			}
			break;
		case INFINITE_MODE:
			depth = 1;
			while (ChessEngine.brainStatus == THINKING)
			{
				ChessEngine.Search(ChessEngine.currentPosition, depth);
				depth++;
			}
			break;
		default:
			ChessEngine.brainStatus = PAUSED;
			break;
		}
		ChessEngine.Stop();

		//// instant final perf /////////////////
		//long time = ChessEngine.watch.GetElapsedTime();
  //      long nps = time>0? 1000 * ChessEngine.nbProcessedNodes / time : 0;
  //      cout << "info nodes " << ChessEngine.nbProcessedNodes << " nps " << nps << endl;
		//////////////////////////////////


		if (ChessEngine.bestMove != MOVE_NULL)
		{
			// Display best move
			cout << "bestmove " <<  move_to_string(ChessEngine.bestMove) << endl;
		}
		else
		{
			// Display no move
			cout << "bestmove -" << endl;
		}

	}
}

// Thread::wake_up() wakes up the thread, normally at the beginning of the search
// or, if "sleeping threads" is used at split time.

void Thread::wake_up() {
	lock_grab(sleepLock);
	cond_signal(sleepCond);
	lock_release(sleepLock);
}


// Thread::wait_for_stop_or_ponderhit() is called when the maximum depth is
// reached while the program is pondering. The point is to work around a wrinkle
// in the UCI protocol: When pondering, the engine is not allowed to give a
// "bestmove" before the GUI sends it a "stop" or "ponderhit" command. We simply
// wait here until one of these commands (that raise StopRequest) is sent and
// then return, after which the bestmove and pondermove will be printed.

void Thread::wait_for_stop_or_ponderhit() {
	/*
	Signals.stopOnPonderhit = true;
	lock_grab(sleepLock);
	while (!Signals.stop) cond_wait(sleepCond, sleepLock);
	lock_release(sleepLock);
	*/
}


// Thread::cutoff_occurred() checks whether a beta cutoff has occurred in the
// current active split point, or in some ancestor of the split point.

bool Thread::cutoff_occurred() const {
	/*
	for (SplitPoint* sp = curSplitPoint; sp; sp = sp->parent)
	if (sp->cutoff)
	return true;
	*/
	return false;

}


// Thread::is_available_to() checks whether the thread is available to help the
// thread 'master' at a split point. An obvious requirement is that thread must
// be idle. With more than two threads, this is not sufficient: If the thread is
// the master of some active split point, it is only available as a slave to the
// slaves which are busy searching the split point at the top of slaves split
// point stack (the "helpful master concept" in YBWC terminology).

bool Thread::is_available_to(Thread* master) const {

	/*
	if (is_searching)
	return false;

	// Make a local copy to be sure doesn't become zero under our feet while
	// testing next condition and so leading to an out of bound access.
	int spCnt = splitPointsCnt;

	// No active split points means that the thread is available as a slave for any
	// other thread otherwise apply the "helpful master" concept if possible.
	return !spCnt || (splitPoints[spCnt - 1].slavesMask & (1ULL << master->idx));
	*/
	return false;
}


// init() is called at startup. Initializes lock and condition variable and
// launches requested threads sending them immediately to sleep. We cannot use
// a c'tor becuase Threads is a static object and we need a fully initialized
// engine at this point due to allocation of endgames in Thread c'tor.

void ThreadsManager::init() {
	//cout << "ThreadManager init called" << endl;
	cond_init(sleepCond);
	lock_init(splitLock);
	//timer = new Thread(&Thread::timer_loop);
	//threads.push_back(new Thread(&Thread::main_loop));
	timer = new Thread(&Thread::ClockThreadLoop);
	threads.push_back(new Thread(&Thread::BrainMainThreadLoop));

	read_uci_options();

}


// d'tor cleanly terminates the threads when the program exits.

ThreadsManager::~ThreadsManager() {

	for (int i = 0; i < size(); i++)
		delete threads[i];

	delete timer;
	lock_destroy(splitLock);
	cond_destroy(sleepCond);

}


// read_uci_options() updates internal threads parameters from the corresponding
// UCI options and creates/destroys threads to match the requested number. Thread
// objects are dynamically allocated to avoid creating in advance all possible
// threads, with included pawns and material tables, if only few are used.

void ThreadsManager::read_uci_options() {

	//maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
	//minimumSplitDepth       = Options["Min Split Depth"] * ONE_PLY;
	//useSleepingThreads      = Options["Use Sleeping Threads"];
	//int requested           = Options["Threads"];

	//TODO: for debug= to be replaced
	int requested = 16; // TEST VALUE 16
	assert(requested > 0);

	while (size() < requested)
		threads.push_back(new Thread(&Thread::idle_loop));

	while (size() > requested)
	{
		delete threads.back();
		threads.pop_back();
	}
}


// wake_up() is called before a new search to start the threads that are waiting
// on the sleep condition and to reset maxPly. When useSleepingThreads is set
// threads will be woken up at split time.

void ThreadsManager::wake_up() const {

	for (int i = 0; i < size(); i++)
	{
		threads[i]->maxPly = 0;
		threads[i]->do_sleep = false;

		if (!useSleepingThreads)
			threads[i]->wake_up();
	}
}


// sleep() is called after the search finishes to ask all the threads but the
// main one to go waiting on a sleep condition.

void ThreadsManager::sleep() const {

	for (int i = 1; i < size(); i++) // Main thread will go to sleep by itself
		threads[i]->do_sleep = true; // to avoid a race with start_searching()
}


// available_slave_exists() tries to find an idle thread which is available as
// a slave for the thread 'master'.

bool ThreadsManager::available_slave_exists(Thread* master) const {

	for (int i = 0; i < size(); i++)
		if (threads[i]->is_available_to(master))
			return true;

	return false;
}


// split() does the actual work of distributing the work at a node between
// several available threads. If it does not succeed in splitting the node
// (because no idle threads are available, or because we have no unused split
// point objects), the function immediately returns. If splitting is possible, a
// SplitPoint object is initialized with all the data that must be copied to the
// helper threads and then helper threads are told that they have been assigned
// work. This will cause them to instantly leave their idle loops and call
// search(). When all threads have returned from search() then split() returns.
/*
template <bool Fake>
Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta,
Value bestValue, Move* bestMove, Depth depth,
Move threatMove, int moveCount, MovePicker* mp, int nodeType) {
assert(pos.pos_is_ok());
assert(bestValue > -VALUE_INFINITE);
assert(bestValue <= alpha);
assert(alpha < beta);
assert(beta <= VALUE_INFINITE);
assert(depth > DEPTH_ZERO);

Thread* master = pos.this_thread();

if (master->splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
return bestValue;

// Pick the next available split point from the split point stack
SplitPoint* sp = &master->splitPoints[master->splitPointsCnt++];

sp->parent = master->curSplitPoint;
sp->master = master;
sp->cutoff = false;
sp->slavesMask = 1ULL << master->idx;
sp->depth = depth;
sp->bestMove = *bestMove;
sp->threatMove = threatMove;
sp->alpha = alpha;
sp->beta = beta;
sp->nodeType = nodeType;
sp->bestValue = bestValue;
sp->mp = mp;
sp->moveCount = moveCount;
sp->pos = &pos;
sp->nodes = 0;
sp->ss = ss;

assert(master->is_searching);

master->curSplitPoint = sp;
int slavesCnt = 0;

// Try to allocate available threads and ask them to start searching setting
// is_searching flag. This must be done under lock protection to avoid concurrent
// allocation of the same slave by another master.
lock_grab(sp->lock);
lock_grab(splitLock);

for (int i = 0; i < size() && !Fake; ++i)
if (threads[i]->is_available_to(master))
{
sp->slavesMask |= 1ULL << i;
threads[i]->curSplitPoint = sp;
threads[i]->is_searching = true; // Slave leaves idle_loop()

if (useSleepingThreads)
threads[i]->wake_up();

if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
break;
}

lock_release(splitLock);
lock_release(sp->lock);

// Everything is set up. The master thread enters the idle loop, from which
// it will instantly launch a search, because its is_searching flag is set.
// We pass the split point as a parameter to the idle loop, which means that
// the thread will return from the idle loop when all slaves have finished
// their work at this split point.
if (slavesCnt || Fake)
{
master->idle_loop(sp);

// In helpful master concept a master can help only a sub-tree of its split
// point, and because here is all finished is not possible master is booked.
assert(!master->is_searching);
}

// We have returned from the idle loop, which means that all threads are
// finished. Note that setting is_searching and decreasing splitPointsCnt is
// done under lock protection to avoid a race with Thread::is_available_to().
lock_grab(sp->lock); // To protect sp->nodes
lock_grab(splitLock);

master->is_searching = true;
master->splitPointsCnt--;
master->curSplitPoint = sp->parent;
pos.set_nodes_searched(pos.nodes_searched() + sp->nodes);
*bestMove = sp->bestMove;

lock_release(splitLock);
lock_release(sp->lock);

return sp->bestValue;
}
*/
// Explicit template instantiations
//template Value ThreadsManager::split<false>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker*, int);
//template Value ThreadsManager::split<true>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker*, int);


// ThreadsManager::set_timer() is used to set the timer to trigger after msec
// milliseconds. If msec is 0 then timer is stopped.

void ThreadsManager::set_timer(int msec) {

	lock_grab(timer->sleepLock);
	timer->maxPly = msec;
	cond_signal(timer->sleepCond); // Wake up and restart the timer
	lock_release(timer->sleepLock);

}


// ThreadsManager::wait_for_search_finished() waits for main thread to go to
// sleep, this means search is finished. Then returns.

void ThreadsManager::wait_for_search_finished() {

	Thread* t = main_thread();
	lock_grab(t->sleepLock);
	cond_signal(t->sleepCond); // In case is waiting for stop or ponderhit
	while (!t->do_sleep) cond_wait(sleepCond, t->sleepLock);
	lock_release(t->sleepLock);

}


// ThreadsManager::start_searching() wakes up the main thread sleeping in
// main_loop() so to start a new search, then returns immediately.
/*
void ThreadsManager::start_searching() {

wait_for_search_finished();

SearchTime.restart(); // As early as possible

Signals.stopOnPonderhit = Signals.firstRootMove = false;
Signals.stop = Signals.failedLowAtRoot = false;

RootPosition = pos;
Limits = limits;
RootMoves.clear();

for (Movevector<MV_LEGAL> ml(pos); !ml.end(); ++ml)
if (searchMoves.empty() || count(searchMoves.begin(), searchMoves.end(), ml.move()))
RootMoves.push_back(RootMove(ml.move()));




////////////////////////////////////////CUSTOM DRAFT CODE
vector<Move> legalMoves;
GetLegalMoves(ChessEngine.currPos,legalMoves);
ChessEngine.InitPossibleNodes(legalMoves);
//if (brainMode == ADJUSTTIME_MODE) UpdateThinkDelay();
ChessEngine.watch.Start();
ChessEngine.brainStatus = THINKING; //<-- global object
////////////////////////////////////////CUSTOM DRAFT CODE




main_thread()->do_sleep = false;
main_thread()->wake_up();

}
*/

/// Thread::idle_loop() is where the thread is parked when it has no work to do.
/// The parameter 'master_sp', if non-NULL, is a pointer to an active SplitPoint
/// object for which the thread is the master.
//void Thread::idle_loop(SplitPoint* sp_master) {
void Thread::idle_loop() {
	// DO NOTHING
	/*
	while(!do_exit){
	while(ChessEngine.brainStatus != THINKING && !do_exit) Sleep(100);
	if(do_exit) return;

	while(ChessEngine.brainStatus == THINKING){

	cout << ">";
	//InjectNodes();

	}
	ChessEngine.watch.Stop();
	}*/


	//// If this thread is the master of a split point and all slaves have
	//// finished their work at this split point, return from the idle loop.
	//while (!sp_master || sp_master->slavesMask)
	//{
	//    // If we are not searching, wait for a condition to be signaled
	//    // instead of wasting CPU time polling for work.
	//    while (   do_sleep
	//           || do_exit
	//           || (!is_searching && Threads.use_sleeping_threads()))
	//    {
	//        if (do_exit)
	//        {
	//            assert(!sp_master);
	//            return;
	//        }

	//        // Grab the lock to avoid races with Thread::wake_up()
	//        lock_grab(sleepLock);

	//        // If we are master and all slaves have finished don't go to sleep
	//        if (sp_master && !sp_master->slavesMask)
	//        {
	//            lock_release(sleepLock);
	//            break;
	//        }

	//        // Do sleep after retesting sleep conditions under lock protection, in
	//        // particular we need to avoid a deadlock in case a master thread has,
	//        // in the meanwhile, allocated us and sent the wake_up() call before we
	//        // had the chance to grab the lock.
	//        if (do_sleep || !is_searching)
	//            cond_wait(sleepCond, sleepLock);

	//        lock_release(sleepLock);
	//    }

	//    // If this thread has been assigned work, launch a search
	//    //if (is_searching){
	//  
	//        assert(!do_sleep && !do_exit);

	//        lock_grab(Threads.splitLock);

	//        assert(is_searching);
	//        SplitPoint* sp = curSplitPoint;

	//        lock_release(Threads.splitLock);

	//        Stack ss[MAX_PLY_PLUS_2];
	//        Position pos(*sp->pos, this);

	//        memcpy(ss, sp->ss - 1, 4 * sizeof(Stack));
	//        (ss+1)->sp = sp;

	//        lock_grab(sp->lock);

	//        if (sp->nodeType == Root)
	//            search<SplitPointRoot>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
	//        else if (sp->nodeType == PV)
	//            search<SplitPointPV>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
	//        else if (sp->nodeType == NonPV)
	//            search<SplitPointNonPV>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
	//        else
	//            assert(false);

	//        assert(is_searching);

	//        is_searching = false;
	//        sp->slavesMask &= ~(1ULL << idx);
	//        sp->nodes += pos.nodes_searched();
	//  

	//        // Wake up master thread so to allow it to return from the idle loop in
	//        // case we are the last slave of the split point.
	//        if (   Threads.use_sleeping_threads()
	//            && this != sp->master
	//            && !sp->master->is_searching)
	//            sp->master->wake_up();
	//	  

	//        // After releasing the lock we cannot access anymore any SplitPoint
	//        // related data in a safe way becuase it could have been released under
	//        // our feet by the sp master. Also accessing other Thread objects is
	//        // unsafe because if we are exiting there is a chance are already freed.
	//        lock_release(sp->lock);
	//  
	//    }
	//}
}


/*
// version of InjectNodes using extern nodeQueue via threads
inline void Thread::InjectNodes()
{
//cout << ">" ; // injetion display
// critical part
lock_grab(ChessEngine.nodeQueueLock);
if(ChessEngine.nodeQueue.empty()){
lock_release(ChessEngine.nodeQueueLock);
return;
}
ChildrenNode currentNode = ChessEngine.nodeQueue.front();
ChessEngine.nodeQueue.pop();
lock_release(ChessEngine.nodeQueueLock);
// end of critical part

if (!currentNode.toBeRemoved)
{
int currentDepth = currentNode.GetDepth();
if (currentDepth > (ChessEngine.maxDepth + 1))
{
ChessEngine.maxDepth = (currentDepth - 1);
//TODO: make those 2 function callable
ChessEngine.UpdatePossibleNodesScores(ChessEngine.maxDepth);
ChessEngine.DisplayBestPve(ChessEngine.maxDepth);
}
if (!currentNode.IsCreatedchildren())
{
ChessEngine.processedNodes += currentNode.Createchildren(ChessEngine.nodeQueue);
}
}

}
*/

void ThreadsManager::DisplayStatus(){
	cout << endl << "THREADS MANAGER STATUS =============== nb of threads:" << this->size() << endl;
}
